Along with Sarah, Trent is Kristina's best friend from before Bree crashed into her life. One of the reasons she connects with him is because he's gay. According to the brief biography she gives when they meet up at Wild Waters, Trent decided to come out on his sixteenth birthday, not just to his family, but to the whole school. Since then, he's been the subject of harassment, social isolation, and bullying, including being "semitortured by some pickup truck cowboys who didn't have a clue about the real meaning of masculinity" (Wild Waters Day Dawned.4). Poor guy.
While her classmates aren't exactly tolerant of his sexuality, Kristina identifies with Trent on a different level because of "the Leigh factor" (Wild Waters Day Dawned.3). Having witnessed her lesbian sister's struggle for acceptance just within their own family, she finds it easy to be cool with one of her best friends liking dudes. Before Bree, at least. Once Bree's on the scene, she kind of looks down on Sarah and Trent, not because of Trent's sexuality, but because they aren't exactly Bree's type.
There is one little layer of tension that Trent and Kristina's relationship causes for her new lifestyle: Trent is Robyn the Reno High Cheerleader's younger brother. As a result, he observes Kristina's friendship with his sister unfolding and totally knows the score. "Trent knew exactly what was with his sister, and so with me," Kristina says. While Sarah may be left bewildered about why their friendship crashed and burned, Trent's inside knowledge of Robyn's activities tells him everything he needs to know.